Snail Kites Prefer Escargot?

Two weeks ago I observed something quite unusual during a Snail Kite survey. I was tasked with meeting the project's Kissimmee area crew to survey a section of the Kissimmee river with them. As field lead of the state wide Snail Kite monitoring crew, I'm used to making some long drives to get to our daily surveys, but this site was only fifteen minutes from our field house. Basking in the luxury of a short drive, I rolled out of bed at the civilized hour of seven a.m., and met the crew for what I expected would be a short and kite-less survey. Kissimmee River can be an incredible spot to see kites when the river floods and creates a healthy floodplain. A rushing river is not much use to a Snail Kite, but when the grassy plains surrounding a river channel flood, shallow, vegetation-rich conditions can arise and provide perfect foraging habitat. A good rule of thumb for kite activity is too little water=no snails, while too much water=too deep for kites to successfully hunt snails. Anyway, in the fall the river floods, and in October we counted nearly 150 kites in one survey, which was among the highest counts we achieved in the state all month. Over the rest of the year however, water levels tend to drop, and our monthly surveys reflect the degraded conditions. Over winter, with water levels clearly already dwindling, we could muster a fifty kite survey, but across our last three spring and summer surveys, the river banks looked bone dry and we counted one measly, probably confused and disoriented kite. I had no reason to expect my most recent survey to be any different. 

As we launched our boat I planned to be on the water for no more than three hours, but rounding a bend in the river six miles in, I was rudely shocked. We came upon a section of the river where land managers had clearly done a prescribed burn recently, and my colleague Melisa pointed to a kite perched on some vegetation. "Oh nice," I thought, "at least we'll have one kite this survey." Shutting the boat off and pulling up to a steep river bank to inspect the bird more closely, I called out to Sandy, who on this day was recording data for us, and I asked her to note one un-banded male kite on the datasheet. Melisa quickly and politely contradicted me by pointing out that the bird was actually a banded female kite. Slightly embarrassed, I double check, and am filled with righteous indignation when I realize I had not made any mistake! My kite had orange legs unmarked by the color bands we apply, a fully blue head, striking red eyes, a bright orange cere, and could not have been anything but adult male. Before I had a chance to argue, it became clear that we were simply looking at different birds. After a cursory scan of the burnt area of the river bank, the three of us realized there were not one, not two, but dozens of kites present. 

What the hell was going on? Prescribed burns provide a whole bunch of ecological benefits, but I had never heard of them helping Snail Kites. Everything I knew about the species told me they need nice, shallow, freshwater wetlands where they can hunt live snails, but here I was watching them in a half mile section of bone dry, scorched, floodplain, scavenging dead apple snails. Melisa and I disembarked on the river bank while Sandy was left with the unenviable task of hanging back to make sure our airboat didn't float away down the river. Sensing I was witnessing an unusual ecological event, I took pictures of the chalky, scorched snail shells and their boiled meat, along with the coal-black mud and stripped bases of plant stems that the dead snails were resting on top of, and then I got to work counting kites. When so many kites are swirling around, actively hunting (or scavenging in this case), and territorially chasing each other, my job becomes quite tricky. In moments like these it's crucial to have a cool, calm, and collected voice assisting you, and luckily, as I was stressing myself out trying to keep track of which kites I had counted and which I hadn't got to yet, Melisa was my guiding light. With her help, after about an hour and a half, we were pretty confident in our count of fifty three total birds. 

After finally getting an accurate count, we continued with the remaining thirty miles of our survey track down the river channel, which turned out about as I expected it to that morning. The unburned river banks were lush and thick, and while beautiful to look at, would have completely concealed the scant puddles of water where apple snails may or may not have been eking out an existence, preventing kite foraging. We saw only two other kites for the rest of our survey. On my drive home that afternoon, I texted my boss to see if she had ever heard of kites scavenging dead snails on this scale, and she hadn't. Performing a cursory literature search online, I did not find any published accounts of such behavior either. 

Hopefully we'll be able to publish some account of this experience in a scientific journal, and maybe more experienced scientists than I can shed some light on this. For what it's worth, with my two years of involvement in this project, my best guess would be that the terrible drought plaguing the state is probably the root cause of this novel foraging strategy. Already, over the last few months, we have been making note of increased instances of unusual foraging. While apple snails make up ~99% of Snail Kite's typical diet, lately, we've observed unusually high instances of them deviating and eating musk turtles, dead fish, a few dead birds, some kind of large crab (pictured below), and now this scorched snail feeding frenzy. We have also observed some fierce intraspecific fighting, which I'm told is also generally uncommon for these kites, and may be another sign of resource scarcity and increased competition. Concealed within the excitement of observing a new and unexpected behavior, it's hard to avoid feeling that the root cause is related to degrading kite conditions throughout the state.